Preparation

Char peppers over gas flame or in broiler until blackened on all sides. Enclose in paper bag 15 minutes. Peel and seed peppers, then cut lengthwise into 1/4-inch-wide strips.

Heat 2 tablespoons oil in heavy large skillet over high heat. Add button mushrooms; sprinkle with salt and pepper and sauté until mushrooms are softened but still hold shape, about 7 minutes. Transfer mushrooms to large bowl. Add 2 tablespoons oil to same skillet. Add shiitake mushrooms; sprinkle with salt and pepper and sauté until soft, about 5 minutes. Transfer mushrooms to same bowl. Heat 1 tablespoon oil in same skillet. Add oyster mushrooms; sprinkle with salt and pepper and sauté until soft, about 4 minutes. Transfer mushrooms to same bowl; reserve skillet.

Toast chiles de árbol in small skillet over high heat until just beginning to darken, about 15 seconds. Transfer 3 chiles to spice mill and finely grind; reserve remaining whole chiles.

Heat 1/2 cup oil in reserved skillet over medium heat. Add onions and sauté until translucent, about 10 minutes. Add garlic and next 5 ingredients, 1/4 teaspoon of ground chiles de árbol, and remaining 6 whole chiles de árbol; stir to coat. Add 3 cups water and both vinegars; season generously with salt. Bring to boil, stirring frequently, then pour vinegar mixture over mushrooms in bowl. Add red pepper strips. Cool completely. Cover and chill overnight. DO AHEAD Can be made 1 week ahead. Keep refrigerated.

Strain mushroom escabeche over large bowl. Arrange drained mushrooms on large platter; discard garlic cloves and bay leaves. Drizzle mushrooms with some of marinade. Garnish with parsley leaves and serve.